Many different types of computing systems have attained widespread use around the world. These computing systems include personal computers, servers, mainframes and a wide variety of stand-alone and embedded computing devices. Sprawling client-server systems exist, with applications and information spread across many PC networks, mainframes and minicomputers. In a distributed system connected by networks, a user may access many application programs, databases, network systems, operating systems and mainframe applications. Computers provide individuals and businesses with a host of software applications including word processing, spreadsheet, and accounting. Further, networks enable high speed communication between people in diverse locations by way of e-mail, websites, instant messaging, and web-conferencing.
A common architecture for high performance, single-chip microprocessors is the reduced instruction set computer (RISC) architecture characterized by a small simplified set of frequently used instructions for rapid execution. Thus, in a RISC architecture, a complex instruction comprises a small set of simple instructions that are executed in steps very rapidly. These steps are performed in execution units adapted to execute specific simple instructions. In a superscalar architecture, these execution units typically comprise load/store units, integer Arithmetic/Logic Units, floating point Arithmetic/Logic Units, and Graphical Logic Units that operate in parallel. In a processor architecture, an operating system controls operation of the processor and components peripheral to the processor. Executable application programs are stored in a computer's hard drive. The computer's processor causes application programs to run in response to user inputs.
In some systems a service processor operates in conjunction with a main processor. The main processor performs most of the processing work including the execution of application program code, whereas the service processor performs routine tasks. These routine tasks include configuring the system components, including configuring the main processor. A present day processing system consists of a collection of entities. These include memory, devices (ethernet adapters, USB adapters, video adapter), and processors, all of which have to work together to accomplish the functions of the computer. These entities may be grouped together based on physical characteristics, for example, how many address/data lines they have, how those lines are driven, what clock speeds they need, etc. These devices are in communication through address and data busses. Entities of one bus must communicate to entities of another bus. The device that conducts information from one bus to another is called a bridge.
An important job of the service processor is to go through the web of buses and configure these bridges so that the individual buses can work together as an effective system. The service processor provides setup information to the main processor, and configures clocks and system voltage sources. The service processor also starts the main processor. After the processor is started, the main processor finishes system initialization by configuring all the specific devices on the busses, starts the operating system and begins executing application programs.
Once the main processor is running, the service processor is relieved of initialization duties and then starts monitoring the system environment. For example, the service processor monitors thermal conditions and if the system gets to hot, the service processor may start a fan. If the system temperature continues to rise, the service processor may slow the main processor so that it consumes less power and dissipates less heat. In a temperature extreme, the service processor may shut the main processor down.
The service processor does not execute application program code and also has its own code space; i.e., the code executed by the service processor is different and separate in memory from the code executed by the main processor. Since the service processor in current systems does not execute the operating system code executed by the main processor, and also does not execute application program code, the service processor power is not fully utilized. Accordingly, there is a need for more efficient allocation of processing functions between a primary processor and a secondary processor to achieve more efficient power consumption.